Two-storey Extensions

Planning Permission

Most 2 storey extensions are not Permitted Development (PD).  However, an extension or addition to your house is considered to be permitted development, not requiring an application for planning permission, provided certain limits and conditions are met. When in doubt, we recommend applying for a certificate of lawful proposed development (CoLU) to confirm your project is PD.

The rules are:

  1. On designated land extensions of more than one storey are not permitted development. * Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.
  2. Extensions (including previous extensions) and other buildings must not exceed 50% of the total area of land around the original house. The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so. * Sheds and other outbuildings must be included when calculating the above 50% limit.
  3. Maximum eaves and ridge height of extension no higher than existing house. If extension is within two metres of a boundary maximum eaves height should be no higher than three metres to be permitted development.
  4. Extensions of more than one storey must not extend beyond the rear wall of original house by more than three metres or be within seven metres of any boundary opposite the rear wall of the house.
  5. Roof pitch of extensions higher than one storey to match that of the existing house, as far as is practicable.
  6. Materials used in exterior work to be similar in appearance to those of the exterior of the existing house.
  7. Any upper-floor window in a wall or roof slope in a side elevation must be obscure-glazed and non-opening unless the parts which can be opened are more than 1.7 metres above the floor of the room in which it is installed.
  8. No balconies or verandas are permitted development.

Planning Cost Calculator

  • Immediate estimate for planning your project
  • Accurate quote emailed within the hour
  • Planning appraisal report emailed to you the same day
  • Consultation call with a Planning Consultant within 24 hours
Get FREE estimate